Disabling onboard graphics.

I'm planning on installing a radeon 9200se to my Emachines 160 using a PCI slot.

1.3GHz Processor
256 ram

(no laughing please, i'm saving for a new system, but this is a quick fix)

It currently has on board graphics, and i understand you dont have to disable this when using an AGP slot, but what about a PCI slot, do you need to disable it then.

Also if you do, can someone tell me how to. I've been into BIOS and when moving down to the graphics card settings, a decription pops up on the right saying 'set to 512 or 1mb' for one setting, and a little below that it says select 'disable onboard graphics' if you you dont want to use it (or someting like that). However I only have an option to have 512 or 1mb, there is no option in the list to disable it.

normally on your bios you can turn off built in graphics. but if not i have seen ways of diabling it through xp, if you make it the primary device on device manger it should work.... sorry my english is rubbish try going on the windows help for more info.....